Boats in the range of 18-30 feet of length are commonly stored on boat hoists. Such hoists are designed to lift the boat from the water in order to prevent problems such as bottom growth and blistering. Many sailboats have keels or rudders whose height is greater than the lifting capacity of the hoist in use. Likewise, many powerboats have outdrives or outboard engines (collectively referred to hereinafter as lower units) whose height exceeds the lifting capacity of the hoist in use. When such boats are lifted on their respective hoists, the lower sections of the keel, rudder or lower unit remain submerged.
A common solution to the problem of bottom growth on these partially submerged appendages is enclosing the appendage in a plastic bag and introducing some chlorine bleach into the interior. While somewhat effective in halting bottom growth, this attempt both introduces pollutants to the waterways and fails to isolate the appendages from the water, thereby allowing blistering of the gelcoat.
There have been introduced other solutions to the problem of bottom growth, such as the Barnacle Sheild by Falcaro U.S. Pat. No. 5,465,676 which supplies an envelope of flexible material supported about the hull by means of a floating frame and into which fresh water is supplied. While this invention is not intended for use on a boat partially submerged in water, it's lessons are applicable. The problems with this type of treatment are the same as that of the more simplistic plastic bag and bleach approach--a failure to isolate the immersed boat appendages from the water.
This invention relates to the field of devices designed to protect the submerged portions of keels, rudders and lower units of boats partially lifted from the water from bottom growth, blistering and related problems which commonly occur to those submerged portions when in continual direct contact with water.
The device of the present invention, an enclosure for partially submerged boat keels, rudders and lower units, is a box-like structure constructed to enclose those described parts extending downwards from the hull of a boat when the boat is lifted from the water on a hoist in such a manner as to prevent direct contact with the water. The device is positioned about the submerged portion of the keel, rudder or lower unit and then emptied of water, resulting in flotation of the upper portions of the enclosure to a level above the surrounding waterline. By thus preventing continuous direct contact with water during periods of storage, the adverse effects of bottom growth and gelcoat blistering are reduced or eliminated, thus enhancing performance underway and reducing maintenance.